A differential amplifier has an advantage of removing common mode noise as compared to other type of amplifier, and is widely used for amplifying baseband signals of a communication device (for example, a mobile phone or a communication terminal conform to a wireless local area network (LAN)).
As the differential amplifier in the related art, a multistage amplifier is known in which differential amplifiers are connected in multiple stages, and Inverse Scaling is applied (for example, see NPL 1). In the Inverse Scaling of NPL 1, a circuit is designed in such a manner that a transistor size of the differential amplifier of each stage is reduced by half in order toward the subsequent stage.
Further, a multistage amplifier is known in which differential amplifiers are connected in multiple stages and a DC offset of the differential amplifier of each stage is corrected by calibration (for example, see PTL 1).